Mechanism of formation of the contractile ring during cytokinesis

1)克隆了裂解酵母的Rho4和Rho5基因。Rho4调节F-肌动蛋白斑块的定位和微管的组织，从而调节细胞壁和隔膜的形成。Rho4的定位受RhoGDI调控，而Rho4的活性受RhoGAP调控。它结合IQGAP，从而促进肌动蛋白聚合。IQGAP在细胞分裂过程中定位于分裂沟。3)C端134残基是Myo2定位到分裂位点的必要条件和充分条件。该区域含有Ser1444，它在间期被磷酸化，但在M期被去磷酸化。这种去磷酸化使MyO2能够靶向MID1，MID1在G2.4)Rho1GEF Rgf1和Rgf2在间期定位于分裂酵母细胞的生长端，在有丝分裂时定位于隔区，并参与细胞壁…的合成更多和隔膜。在有丝分裂过程中，RGF3在分裂部位积累形成环，随着胞质分裂的进行，环收缩。RGF3被认为通过激活Rho1.5来控制收缩环和隔膜的形成。)我们通过用肌球蛋白S1修饰F-肌动蛋白来确定分裂酵母细胞F-肌动蛋白缆线中F-肌动蛋白的方向性。在相间电缆中，F-肌动蛋白的带刺末端在相间时面向细胞的生长端。在有丝分裂过程中，它发生了逆转。我们提出了一个假说，肌球蛋白V在间期将细胞极化生长所需的物质运输到细胞末端，而在有丝分裂期间将分裂所需的物质运输到分裂部位。6)分裂酵母肌动蛋白解聚因子adf1在间期定位于F-肌动蛋白片层，在有丝分裂和胞质分裂时定位于收缩环。ADF1通过其F-肌动蛋白切断活性参与收缩环的形成。它与细胞内F-肌动蛋白的结合是与原肌球蛋白CDC8竞争的。研究还发现，Adf1与肌球蛋白II协同作用形成了收缩环。我们认为ADF1对于收缩环的形成和稳定性是必需的。较少

1)rho4 and rho5 genes of fission yeast was cloned. Rho4 regulates localization of F-actin patches and organization of microtubules, and thereby formation of cell wall and the septum. Localization of Rho4 is regulated by RhoGDI while activity of Rho4 is regulated by the RhoGAP Rga92)Sea urchin Cdc42 showed 87% homology to human Cdc42. It binds IQGAP and thus enhancesw actin polymerization. IQGAP localizes to the cleavage furrow during cytokinesis.3)It was established that the C-terminal 134 residues are necessary and sufficient for localization of Myo2 to the division site. This region contains Ser1444 which is phosphorylated during interphase but dephosphorylated during M-phase. This dephosphorylation enables Myo2 to target Mid1 which is transmitted from the nucleus to the equatorial cortex during G2.4)The Rho1GEFs Rgf1 and Rgf2 are localized to the growing ends of fission yeast cell during interphase, while to the septum region during mitosis and are involved in synthesis of cell wall … More and the septum. Rgf3 accumulates at the division site forming a ring during mitosis, and the ring contracts as cytokinesis progresses. Rgf3 is considered to control formation of both the contractile ring and the septum through activation of Rho1.5)We determined directionality of F-actins in the F-actin cables in fission yeast cells by decorating the F-actins using myosin S1. The barbed end of the F-actins in the interphase cables face the growing end of the cell during interphase. During mitosis, it reversed. We proposed a hypothesis that myosin V transports materials necessary for polarized growth of the cell to the cell ends during interphase, while transports those necessary for division to the division site during mitosis.6)Fission yeast actin-depolymerizing factor Adf1 is localized to the F-actin patches during interphase and to the contractile ring during mitosis and cytokinesis. Adf1 is involved in formation of the contractile ring through its F-actin-severing activity. Its binding to F-actin in the cell is competitive with the tropomyosin Cdc8. It was also found that Adf1 cooperates with myosin-II in formation of the contractile ring. We propose that Adf1 is necessary for formation and stability of the contractile ring. Less